Renée’s Platonic Mobile

Alexandria Jones struggled to think of a Christmas gift that a one-month-old baby could enjoy, but finally she got an idea.

She cut empty cereal boxes to make regular polygons: 6 squares, 12 regular pentagons, and 32 equilateral triangles. Using small pieces of masking tape, she carefully formed the five Platonic solids. Then she mixed flour and water into a runny paste. She tore an old newspaper into small strips and soaked them in the paste. She covered each solid with a thin layer of paper.

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Egyptian Math: Fractions

I have been enjoying James Tanton’s website. In this video, Tanton explains a foolproof method for creating Egyptian fractions:

See more posts on Egyptian math.


howtosolveproblemsWant to help your kids learn math? Claim your free 24-page problem-solving booklet, and sign up to hear about new books, revisions, and sales or other promotions.


Math Project: Measure the Earth

Tomorrow, September 23, is the equinox — when night and day are equally balanced (or would be, if the sun appeared as a point, rather than a disc). If we lived on the equator, the sun would appear directly overhead at noon and would cast no shadow. Therefore, it’s a great day to perform Eratosthenes’ experiment of measuring the earth:

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Math History Tidbits: The Battling Bernoullis

July 27th is Alex’s birthday. She shares it with Johann Bernoulli, an irascible mathematician from the late 17th century. This coincidence intrigued her enough that she wrote a research paper on Johann and his mathematical brother, titled “Jeering Jacob and Jealous Johann.”

Of course, to make the alliteration work, she had to mispronounce Johann’s name — but she figured he kinda deserved that. Read the historical tidbits below to find out why one writer said the Bernoulli brothers were “the kind of people who give arrogance a bad name.”*

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One Day Only: Number Stories of Long Ago

For all those who missed it last time, now is your chance: Number Stories of Long Ago will be available Tuesday, January 20, from Homeschool Freebie of the Day.

David Eugene Smith tells stories set in different historical eras, showing how different mathematical concepts were developed and became a part of civilization. Wonderful!

For Those Who Missed It

If you missed the Homeschool Freebies edition, Number Stories of Long Ago is also available as a real book or (at least in the U.S.) as a scanned library book from Google Books.

Or try downloading a copy for your Kindle (or Nook, Kobo, Sony Reader, etc.):


howtosolveproblemsWant to help your kids learn math? Claim your free 24-page problem-solving booklet, and sign up to hear about new books, revisions, and sales or other promotions.

Math History Tidbits: Agnesi, Euler, and China

Alexandria JonesI’ve fallen behind on my project of transcribing my Alexandria Jones stories. Finally, here are a few more tidbits from math history, along with links to relevant Internet sites and a few math puzzles for your students to try.

I hope you find them interesting.

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A Mathematician for President

[Image courtesy of the Images of American Political History.]

In 1876, a politician made mathematical history. James Abram Garfield, the honorable Congressman from Ohio, published a brand new proof of the Pythagorean Theorem in The New England Journal of Education. He concluded, “We think it something on which the members of both houses can unite without distinction of party.”

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Number Stories Is Back, Very Limited Time Only

If you missed Number Stories of Long Ago last time, it is available as a free downloadable pdf file at the Homeschool Freebie of the Day Labor Day Weekend/End of Summer Bash.

This offer should work for those who live outside the U.S. and were unable to read the Google Books file.

But act quickly!

The offer is only good “until Monday night” — and I don’t know which time zone they’re in.


howtosolveproblemsWant to help your kids learn math? Claim your free 24-page problem-solving booklet, and sign up to hear about new books, revisions, and sales or other promotions.

Free Math History: Number Stories of Long Ago

If you teach elementary children, check out this read-aloud math history resource from Homeschool Freebie of the Day:

Number Stories of Long Ago
by David Eugene Smith

[This download is available for one day only. If you missed it, see the end of this post for other ways to get the book.]

From the Preface

“These are the stories that were really told in the crisp autumn evenings, the Story Teller sitting by the fire that burned in the great fireplace in the cottage by the sea. These are the stories as he told them to the Tease and the rest of the circle of friends known as the Crowd. Sitting by the fire and listening to the stories, in the lights and shadows of the dancing flames they could see the forms of Ching and Lugal and all the rest with their curious dress of long ago…”

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